Aligned with the peak carbon and neutrality goals，the mechanized construction of roadbed drainage ditches should consider not only construction efficiency and economic factors but also carbon emissions.This study，centered on the Meng-LYU highway，devised approaches to calculate roadbed drainage ditches' carbon emissions and investment costs across three stages：building material production，transportation，and construction.By introducing the concept of carbon trading to align carbon emissions and investment costs，a comprehensive comparison was conducted between the conventional supporting formwork method and the hydraulically powered sliding formwork method regarding equivalent carbon emissions.An orthogonal experiment was conducted involving the upper length of the roadbed drainage ditch，pouring thickness，haul distance，and construction length as key factors.A comparison was made between the equivalent carbon emissions of the two methods，and the influence sensitivity of these factors was analyzed.The research shows that both pouring thickness and construction length have a significant impact on the equivalent carbon emissions of the construction methods.The contribution of equivalent carbon emissions in the material production stage is higher in the traditional formwork，whereas in the material production and construction stages，it is higher for the h ydraulically powered sliding formwork.The hydraulically powered sliding formwork exhibits superior equivalent carbon emissions compared with traditional formwork.The overall decarbonization rate throughout the construction phase is 85.58%.Notably，the equivalent carbon emissions in all stages are lower than those of the traditional supporting formwork，with higher decarbonization rates observed in the construction and transportation stages，reaching 91.92% and 85.06%，respectively.Therefore，choosing the hydraulically powered sliding formwork method for roadbed drainage construction is recommended.